1. Field of the Invention
The present invention relates to a weft inserting control device for fluid jet type loom for controlling weft reaching timing with relation to a rotation phase of a main shaft of the loom in weft insertion in the fluid jet type loom.
2. Description of the Related Art
Hitherto, in order to converge a dispersion of weft insertion completed timing for a rotation phase of a main shaft of a loom (referred to as weft reaching angle, hereinafter) at a predetermined weft reaching angle, an average deviation, which is an average of difference between an actual reaching angle and an objective reaching angle of weft yarn, has been calculated for every predetermined number of weft insertion times (referred to as picking number, hereinafter). It is arranged that, when the average deviation passes over a predetermined allowable range, fluid jet pressure of a main nozzle or an auxiliary nozzle for weft-inserting be controlled so that the reaching angle would be within the allowable range.
There is also proposed a method for measuring weft inserting power for each weft insertion to accumulate a difference between the weft inserting power and a reference value, and then, controlling the pressure of fluid supplied to a weft inserting nozzle or the rotating number of the main shaft of a loom when the accumulated value passes over an allowable range, as disclosed in a bulletin of Japanese Patent Publication No.39735/1994.
In the case of the former related art described above, however, it is difficult to determine a certain picking number for calculating the average deviation. Excessively large picking number leads to bad response for a rapid change of a weft reaching angle in changing supplied weft where a sort of weft is changed, which sometimes causes a unit to be out of control and stopped. On the contrary, excessively small picking number for calculating the average deviation leads to oversensitive response of a controlling system for a temporary rapid change of the weft reaching time even when the weft reaching angle is almost stable within the reference value, so that the pressure of a weft inserting nozzle would be changed and the reaching angle would not be stable in a converging direction to the contrary, which sometimes causes large dispersion of the reaching angle.
In the case of the latter related art described above, the response for a rapid change of the weft reaching angle can be better in controlling than the former related art described above. It is also difficult, however, as well as the above to determine an allowable range of the accumulated value. Excessively wide allowable range leads to inferior response in controlling similarly to the above, while excessively narrow allowable range leads to oversensitive response also for insignificant deviation of the reaching angle, both of which cause a problem that the reaching angle of weft is not stable. Thus, there have been problems of response and stability in controlling, which are conflicting each other, remaining.
In view of the above-described problems of the related art, the invention has been made and is aimed to provide a weft inserting control device for fluid jet type loom in which pressure change would be made small even at a small controlling picking number in a simple structure so that the response in controlling weft insertion can be better as well as the stability can be improved.
Specifically, the invention is concerned with a weft inserting control device for fluid jet type loom provided with a weft insertion detecting unit for detecting dispersion of a weft reaching angle in a predetermined control cycle such as one or a plurality of picking numbers, for example; a first comparing unit such as a control device for comparing a detection value of the weft reaching angle given by the weft insertion detecting unit with a reference value showing an allowable range of the dispersion; and a second comparing unit for comparing the detection value with a threshold value showing a threshold in controlling the dispersion, the weft inserting control device comprising a controlling unit such as a control device for controlling the weft reaching angle on the basis of the detection value and a result of the comparison carried out by the first comparing unit. Further, the controlling unit controls the weft reaching angle by reducing a predetermined amount of the detection value and by using the threshold value as the detection value, for example, when the second comparing unit reveals the detection value to be over the threshold value.
The controlling unit for the weft reaching angle controls supplied fluid pressure of the weft inserting nozzle, the timing of weft insertion, the rotation number of a main shaft of a loom or such in accordance with fuzzy reasoning corresponding to the above detection value.
The weft inserting control by the controlling unit of the detection value may be carried out when the detection value becomes same as or more than the reference value for every weft insertion, for average deviation of a plurality of weft insertion, or for one or plural picking time(s) in a predetermined plurality of picking. The above control can also be carried out when the detection value passes over the reference value successively for a plurality of picking times.